In June, 49ers coach Jim Harbaugh took aim at the Seahawks’ run of performance-enhancing drug infractions, only adding fuel to an already fierce rivalry between the San Francisco coach and Seattle counterpart Pete Carroll. Cornerback Richard Sherman came right back at his old college coach, saying he had no relationship with Harbaugh and wouldn’t engage in any back and forth.

Three years after the NFC West became known as the NFC Worst, when Seattle reached the playoffs with a losing record, this just might be the NFL’s tightest and most talented division.

“We’re going to be good. We’re going to be fine,” 49ers running back Frank Gore said. “Everybody in our division, we know what they are.”

Here are five things to watch in the NFC West:

ONE MORE WIN NEEDED: After clicking right away with top target Michael Crabtree last year when he took over as starter, Colin Kaepernick will look to establish the same type of chemistry with Boldin.

The Niners traded for Boldin, who helped Baltimore beat them 34-31 in the Super Bowl, leaving San Francisco determined to get back and win the franchise’s sixth Lombardi Trophy with Kaepernick and a stingy defense leading the way.

Boldin is eager to play with an athletic quarterback like Kaepernick, who is coming off a busy offseason.

“Everything doesn’t come overnight,” Boldin said. “The early success in practice is sign of how good the quarterback is.”

With top 2012 receiver Crabtree sidelined at least until November, Boldin will take on a greater role as Kaepernick’s No. 1 option, while tight end Vernon Davis is hoping for a better connection with Kaepernick.

“Chemistry is the most important thing,” Kaepernick said. “Anquan Boldin makes things easier on quarterbacks. He’s a savvy guy and knows the weak spots in an opposing defense.”

PACIFIC NORTHWEST CONTENDER: The Seahawks have their own young, flashy quarterback and believe Russell Wilson can get them back to the playoffs. Wilson led Seattle oh so close to the NFC title game as a rookie, and he’s back with bigger expectations and reliable running back Marshawn Lynch ready to lead the way.

Not to mention Jermaine Kearse, who called his kickoff return to Wilson before running one 107 yards for a touchdown in a 40-10 preseason whipping of the Broncos.

Seattle, with a deep secondary that should rank among the best in football, is poised to build on last year’s 11-5 finish — and do all it can to take down San Francisco.

“We have an elite group of DBs back there,” cornerback Richard Sherman said. “Just as we have to deal with them, they have to deal with us.”

RAM-TOUGH OUT: Coach Jeff Fisher tweaked a roster that went 7-8-1 — an impressive 4-1-1 in the West — but pushed the 49ers to a tie on their home field, then beat San Francisco in St. Louis. That should give the Rams plenty of confidence against the two-time defending division champs.

They must make up for the key losses of running back Steven Jackson and wideout Danny Amendola.

“We need to tackle better, we’ve got to get our return game going and we’ve got to get the ball in the end zone, and get used to doing that,” Fisher said.

Apparently, St. Louis knew exactly what the 49ers would do last season.

New Niners safety Craig Dahl insists St. Louis game-planned perfectly for San Francisco’s schemes in 2012 when he played for the Rams. They left Candlestick Park with a tie, then won in overtime at home. Both teams missed overtime field goals in a 24-24 finish on Nov. 11, the NFL’s first tie in four years.

“We had a few tips off of film. We were able to differentiate between run and pass early,” Dahl said. “That kind of gave us an added benefit on defense. In St. Louis, the mentality was we always looked up to the 49ers as the staple of the NFC West.”

ACCOUNTABLE CARDINALS: New coach Bruce Arians is all about holding the Cardinals accountable.

Arians, NFL Coach of the Year as an interim in Indianapolis last season, is eager to prove himself. Same for new quarterback Carson Palmer in his 13th NFL season. They are counting on a scrutinized offensive line to protect Palmer after the Cardinals allowed an NFL-high 58 sacks last year.

“Going all the way back to the first day I got here, it was either you’re going to be a woe-is-me group of guys or you’re going to take this as a challenge, a slap in the face,” Arians said. “I think they took it as a challenge. They know how talented they are.”

Larry Fitzgerald’s versatility in the receiving game playing multiple positions will be key for the Cardinals.

“For us to be the dominant team we know we’re capable of, we have to keep teams off balance, be able to run effectively, and be able to pass, be efficient in red zone and third-down percentage,” Fitzgerald said.